This brief presents research findings obtained from a broad, but not exhaustive, review of research studies relevant to the prevention of suicide among law enforcement officers. Contents include the prevalence of suicidal thoughts and behaviors among officers, relevant risk and protective factors, effective strategies and best practices for preventing suicide among officers, and knowledge gaps that require additional research. The discussion of evidence-based strategies and best practices notes that research indicates suicide prevention programs are more likely to succeed when they are comprehensive, which involves combining multiple strategies that impact risk and protective factors at various levels of influence (individual, interpersonal, community, and societal). Areas of influence discussed in relation to law enforcement officer suicide are leadership and culture, access to culturally competent mental health services, peer support, suicide prevention training and awareness, event response, family support, and limiting access to means of suicide. Among the knowledge gaps identified are suicide-related data, the effectiveness of preventive strategies and practices, and suicide prevention among subgroups.